Illumination devices of this type are often used for illuminating planar areas. Conventional semiconductor chips often have a comparatively narrow-angled emission characteristic, so that a large part of the radiation generated by the semiconductor chip is emitted into a comparatively narrow solid angle range. A large-area illumination with a semiconductor chip of this type is made more difficult on account of the narrow-angled emission characteristic of the semiconductor chip. An optical element can be used to widen the emission characteristic.
An optical element of this type is described in U.S. Pat. No. 4,907,044, for example. The semiconductor chip is in each case surrounded by the optical element by moulding. FIG. 4 of U.S. Pat. No. 4,907,044 shows a radial LED with an optical element of this type, while FIG. 8 shows a so-called overmould LED design with the optical element. In both designs, firstly the semiconductor chip is contact-connected on the connections and subsequently surrounded by the optical element, the overmould design, in contrast to the radial design, being suitable for surface mounting. On account of the semiconductor chip being encapsulated on all sides by the optical element, there is an increased risk of damage to the optical element in the case of these designs with high radiation power, for instance on account of the heat loss arising during the generation of radiation. Accordingly, the components shown in U.S. Pat. No. 4,907,044 are of only limited suitability for high-power applications for generating high radiation powers with a correspondingly high lost heat.